1. Field of the Invention
The present invention generally relates to an electromagnetic relay and a method of manufacturing the electromagnetic relay.
2. Description of the Related Art
An electromagnetic relay such as a relay is an electronic component which controls electric power to be turned on or off by using an electric magnet. If the above electromagnetic relay is used to control high voltage or direct current, arcs may be generated between contacts of the electromagnetic relay to thereby shorten its operating life of the electromagnetic relay.
Therefore, an example of an improved electromagnetic relay includes a permanent magnet in the vicinity of its contacts. With this example of the electromagnetic relay, arcs generated at a time of separating the contacts are cleared off by applying a force generated by a magnetic field of the permanent magnet. Thus, the power may be turned off within a short time.
An example of a switch may suppress damage caused by arcs in contacts by providing an arc runner in the vicinity of the contacts.
Although arcs may be quickly broken by methods described in Patent Documents 1 to 3, the arcs in the contacts may not be prevented from being generated, so that the arcs are still generated for a short time. Therefore, there is a case where the contacts and parts in the vicinity of the contacts are damaged by the arcs. Then, the operating life of the electromagnetic relay is shortened to thereby degrade safety and reliability of the electromagnetic relay.
Further, if a casing of an electromagnetic relay is formed by a resin material such as a molding resin, generated arcs may contact the resin material to thereby generate an organic gas from the resin material. In this case, if a component of the generated organic gas adheres to a contact or the like, an electric conduction failure may be generated in the contacts or the like. Especially, a yoke or the like made of a magnetic material may be used to efficiently apply a magnetic field in the vicinity of the contacts. The generated arcs are apt to be attracted by the above yoke. Then, the attracted arcs may be easily transferred to the resin material to thereby generate an organic gas. Further, heat generated by the arcs attracted by the yoke or the like is transferred to the permanent magnet. Then, there are problems that the temperature of the permanent magnet is increased to weaken the magnetic power of the permanent magnet.
The embodiments described herein are provided in consideration of the above. An object of the present invention is to provide an electromagnetic relay with high reliability and safety which has a structure of preventing arcs from being attracted in which a yoke for applying a magnetic field to contacts and positions near the contacts. Especially, the object of the present invention is to provide an electromagnetic relay with high reliability and safety used for a voltage higher than that of a commercial power supply, a direct power source, and so on.
Another object of the present invention is to provide a manufacturing method of an electromagnetic relay with high reliability and safety in which arcs can be rapidly removed from contacts and, if the arcs are generated, the operating life of the electromagnetic relay is not affected by the generated arcs. Especially, another object of the electromagnetic relay and the manufacturing method of the electromagnetic relay is to ensure high reliability and safety even if the voltage higher than that of the commercial power supply, the direct power source and so on are controlled by the electromagnetic relay.    [Patent Document 1] Japanese Laid-open Patent Publication No. 2001-176370    [Patent Document 2] Japanese Laid-open Patent Publication No. 2009-87918    [Patent Document 3] Japanese Patent No 2658170